Time-lag cathode circuit arrangement



March 16, 1937. E. LAZZARINI 2,073,701

TIME LAG CATHODE CIRCUIT ARRANGEMENT Filed April 10, 1934 INVENTOR ATTORNEY 30 filament circuit.

Patented Mar. 16, 1937 UNITED STATES PATENT OFFICE TIME-LAG CATHODE CIRCUIT ARRANGEMENT Eugen Lazzarini, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphie m. b. H., Berlin, Germany, a corporation of Germany Application April 10, 1934, Serial No. 719,841 In Germany May 2, 1933 2 Claims.

5 improve the control of cathode circuits.

It is known that when starting the operation of indirectly heated tubes of more than average power, the connection of the plate potential supply must be delayed until the indirectly heated electron emission surface of the cathode has been uniformly incandesced. As a general rule this takes about from 45 to 65 seconds. For the purpose of insuring the said lag in the connection of the plate potential, recourse in the prior art has a usually been to a mechanical time switch. However, such a device is comparatively cumbersome and expensive.

Now, according to this invention a relatively small and inexpensive indirectly heated auxiliary tube is provided instead of a mechanical time-lag switch of the kind before mentioned.

One exemplified embodiment of the basic idea of the invention is schematically illustrated in the drawing. Referring to the latter, a is an indirectly heated transmitter tube of comparatively large power, for which connection of the plate voltage source must be effected a certain length of time after connection of the heating or The plate circuit of the same contains the switch knife 7) of a time-lag switch whose energizing winding 0 is contained in the plate circuit of an auxiliary tube d of lower power which is also of the indirectly heated type. The

2:5 auxiliary tube cl is heated from the same transformer e as the transmitter tube a, thus insuring the same degree of heat being applied to each tube.

I claim:

1. A time delay circuit arrangement to retard the connection of the direct current voltage of a 5 comparatively large power transmitter tube comprising a source of anode potential, a resistance across said anode potential source, a relay having its armature connected in series with one side of said source of anode potential and the anode 1 mediate point on said resistance and in series with 15 an indirectly heated auxiliary tube anode which tube is connected at its cathode to the other side of said plate supply.

2. A time delay circuit arrangement to retard the connection of the direct current voltage of a "comparatively large power transmitter tube comprising a source of anode potential, a resistance across said anode potential source, a relay having its armature connected in series with one side of said source of anode potential and the anode of said transmitter tube, the other side of said voltage supply being connected to the cathode of said transmitter tube, said relay having its winding energized by being connected to an intermediate point on said resistance and in series with an indirectly heated auxiliary tube anode which tube is connected at its cathode to the other side of said plate supply, and a transformer for heating the cathodes of both the transmitted tube and said auxiliary tube.

EUGEN LAZZARINI. 

